Last Light, a 8x8 Patches puzzle
Arrow keys move. Enter starts a rectangle; arrows resize it; Enter places it. Escape cancels. Delete removes a patch. Control or Command Z undoes.
About this board
The hardest board in the 8x8 set. Only the tall 6 in the bottom-left corner is fixed at the start, and six clues give no number, two of them with 59 possible patches each. Most placements here are settled by elimination rather than counting: you keep finding rectangles that would leave a neighbour with nowhere to go. It takes four rounds of checking, the most of any 8x8.